Have you ever watched 'Kissing Cousins'? It's an independent movie (you can watch for free on youtube). It's about amir, a 'professional heartbreaker', who's cynical about relationships. His friend is getting married but doesn't want him as best man because of 'bad relationship karma'. Then Amir meets his long lost cousin and as a joke they pretend that she's his girlfriend but then they start to develop feelings for each other.